Goodwill and Intangible Assets - Goodwill Business Segments (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2020	$ 14,653
Other adjustments(1)	(1)
Balance as of September 30, 2021	14,652
Credit Card
Goodwill [Roll Forward]
Balance as of December 31, 2020	5,088
Other adjustments(1)	(1)
Balance as of September 30, 2021	5,087
Consumer Banking
Goodwill [Roll Forward]
Balance as of December 31, 2020	4,645
Other adjustments(1)	0
Balance as of September 30, 2021	4,645
Commercial Banking
Goodwill [Roll Forward]
Balance as of December 31, 2020	4,920
Other adjustments(1)	0
Balance as of September 30, 2021	$ 4,920